Process of improving lubricating oils by treating with hydrofluoric acid and silver fluoride



Nov. 28, 1950 P. H. CARNELL 2,53,723

PROCESS 0F IMPROVING LUBRICATING OILS BY TREATING WITH HYDROFLUORIC ACID AND SILVER FLUORIDE Filed Deo. l5, 1947 A T7' ORNE V5 Patented Nov. 28, 1950 PROCESS OF IMPROVING LURICATING GILS BY TREATING WITH HYDRO'- IIzULltI()A ACID AND SILVER FLUORIDE Paul H. Carnell, Alma, Mich., assigner to Phillips Petroleum Company, a corporation of'DcIaware Application December 15, 19471, SerialNmf'QLS Claims. l

This invention relates tothe treatmentr of lubrioating oils to improve their properties. In one oi its more specific aspects, it relates to a treatment. of a lubricating oil which improves its viscosity index.

I have discovered that treatment of a lubricating` oilf with substantially anhydrous hydrofluoric acid, a low-boiling hydrocarbon, such as. iscpentane, and silver nuoride vlillimprove the viscosity index of the oil.

Lubricating oil referred to herein, includes all suchproducts and their base stocks vvhichA have. a viscosity Within. the range. of about 32. Si U.. S. `(Saybolt` Universal seconds) at 210 F- to about 3,50S. U. S., at 210i F., and as. are usually understood. to` bel covered by this term by those skilled in. the4 art. It includes lubricating oil stockssuch as paraiiin-base stock, naphthenebase stock., synthetic-base stock, and mixed-base stock,1 which are reiined for use asy engine lubricants..

The hydrofluoric acid and silver fluoride used in` theV practice of this invention, may be of the quality of the commercial products. The hydrofluoric acid, referred to as substantially anhydrous hydrofluoric acid, may contain. small amounts of sulfur dioxide (usualy less than l Weight per cent), Water, and other impurities.

Iy have found that silver fluoride, when used in conjunction with hydrouoric acid and a. lowboiling hydrocarbon for the treatment of lubrii eating oils, is unexpectedly effective in producing improved lubricating oils. In particular, when a lubricating oilv is treated with a mixture of hydrofluoric acid, a low-boiling hydrocarbon,

such as isopentane, and .silver fluoride, .a pronounced improvement in the viscosity index of the oil is obtained. However, if silver chloride is substituted for silver fluoride in the above-men.- tioned mixture, the viscosity index of. the oil is not. improved. substituted for silver fluoride in the above treatment there is no improvement in viscosity index.

The effectiveness of a given promo-ter, in this hydroiluoric acid process for treating lubricating oils, appears tobe in part, a matter of its solubility in hydroiluoric acid. Thus, silver fluoride is an active promoter and is soluble in hydrouoric acid, Whereas silver chloride and lead uoride are inactive and relatively insoluble in hydrofluoric acid.

An object of the present invention is to provide a novel and improved method for improving lubricating oils. Another object is to provide a method for improving natural lubricating oils.

Another object is to provide a method for improving synthetic lubricating oils. Another object is to provide a method for improving mixedbase lubricating oils. Another object is to provide `a method for improving the viscosity index of lubricating oils. Other objects and advantages Likewise, when lead iiuoride. is .1

of this invention. Will become` apparent from the accompanying disclosure and discussion.

Broaclly speaking, my invention comprises a process for improving lubricaitng oil by contacting the lubricating, oil with substantially anhydrous hydrofluoric acidi.. and silver-fluoride. Innapreferred` embodiment.. a low-boiling hydrocarbon is also includedin the.Y reaction mixture.

Generally speaking, lubricating oil, .substantialy anhydrous hydrorluoric acid, a. low-boiling liquid hydrocarbon, such as isopentane, andA finely divided silver' fluoride are introduced to a contact. chamber. Usually satisfactory results can be obtained with this process if temperatures within the range of about 20 to about 40 C. and pressures. of about atmospheric pressure are used. However, with particular oils, it may be desirable to use-'elevatedtemperatures as high as 3D0- and superatmospheric pressures. `The contact time will generally vary from about `20` to about` 12.() minutes,` depending on the type. of agitation used, degree or oil improvement. desired', etc. Suitable volume ratios of. oil to hydrofiuoric acid to light hydrocarbon are about 1:3.:'5 to about 5:31zl, but,A preferably about. 121:1. The weight cf `silver fluoride required. is aboutA l to about l0 weight. per cent of the acid present'.

A better understanding of my invention may be had by referring to the accompanying schematic now diagram of apreferred embodiment.v

Referring to the attached diagram, a low-boileing hydrocarbon, such as isopentane, hydro-uoric acid and silver fluoride, and lubricatingY oil are charged to contacter l0 through lines i i, i2, and I3 respectively, where they are agitated the required length of time, usually for about' 2i) to about minutes, at a moderate or elevated temperature. The treated mixture is passed through line I4 to settler I6 Where it is separated into an upper layer consisting of lubricatingoil and hydrocarbons boiling below the lubricating oil range, part oi which are formed by chemical reaction in contacter lil, and possibly some suspended silver fluoride; and a lower layer consisting of hydrouoric' acid, silver fluoride, and acid soluble organic materials. The lower layer from settler i6 is passed through line il to fractionator l, and; the upper layer is passed throughline i9 to fractionator 2Q.. Hydrollucric. acid from frac.- ticnator i8 is removed through line` l5 andrecycled to contacter lil. The silver iiuori'de-acid solubleoil mixture from the kettle of fractionator i3.' is passed through line 2l te recovery unit 22.. Generally, the silver iluoride may be recovered from the acid-soluble oil by filtration. However, when the acid soluble oil is unusually heavy, .it maybe 4desirable to add a suitable organic solvent before ltering, which is .introduced through line 25. The recovered silver fluoride, to whichA has been added hydrofluoric acid, is recycled from 3 unit 22 to contactor I0 as a slurry, through line 23.

The oil and solvent from recovery unit 22 are passed through line 24 to recovery unit 26 where the solvent is removed for recycle through lines 21, 25, and 2i to unit 22. The oil from unit 2t is recovered through line 28 as a by-product of the process. The low-boiling hydrocarbon from fractionator 20 is recycled to contactor I0 through line 29. Other relatively light hydrocarbons from ,i

fractionator 29, distilling below the lubricating oil boiling range, may be recycled'to contacter l0 through line 29 or withdrawn as by-products of the process through line 30. Lubricating oil from the kettle of fractionator 20 is withdrawn through line Si as the product of the process. If desired, this product may be passed to the silver iluoride and oil-solvent recovery units through line 32 to remove any small amounts of suspended silver fluoride. The recovery of silver fluoride from the product lubricating oil may be carried out in the same apparatus as that used in the processing of the acid soluble oil for silver iiuoride recovery. The treatment of the two must be separate, however, to avoid contamination of the product o1] with acid soluble oil.

Various additional valves, pumps, and other conventional equipment necessary for the successful practice oi this invention will be familiar to one skilled in the art and have been omitted from this schematic drawing for the sake of clarity.

To further illustrate some of the many aspects of this invention, the following specific example is given.

A W2-liter steel bomb was charged with hydrotionating column to remove light ends. The following data were obtamed:

Charge Run @il 1 2 3 4 1,000 1, O00 1,000 1, 000 1,000 1,000 1,000 1, 00() 1,000 1,000 l, 000 1,000 NOD@ 0) (2) (3) Halide, grams. 100 100 loo Product Oil Viscosity, l0() F, S. U. S 388. 3 374. 9 318. 6 372. 2 356. 3 Viscosity, 210 F, S. U. S 55. 52 55.17 53. 63 54. 79 54, 42 Viscosity index (Dean & 85 87 99 86 85 Davis). A. PA I. gravity 28. 4 28. 6 31. 6 28. 7 28. 7

1 Silver iuoridc. 2 Silver chloride. 3 Lead fluoride.

The data of run 2 show that when a given lubricating oil is treated with a mixture of hydroiuoric acid, isopentane, and silver fluoride, at room temperature, the viscosity index of the product oil is about 12 units higher than the viscosity index of the oil treated with a hydroiiuoric acid-isopentane mixture in the absence of silver fluoride. improvement in the oil than is obtained by leaving a metallic halide out of the treatment altogether, as shown in run 1.

Although this invention has been described and The data from runs 3 and 4 show less 'g exemplied in terms of its preferred modication, it is understood that various changes may be made without departing from the spirit of the process as disclosed and expressed in the claims.

I claim:

1. A process for improving the viscosity index of a lubricating oil which comprises treating a lubricating oil with a reagent consisting of a mixture of substantially anhydrous hydrofluoric acid and silver fluoride.

2. The process of producing a lubricating oil of improved viscosity index which comprises treating a lubricating oil with a reagent consisting of a mixture of substantially anhydrous hydrouoric acid and solid silver fluoride in the presence of a low-boiling liquid hydrocarbon diluent, said treatment taking place at a temperature in the range of about 20 to about 300 C., at a moderate to high pressure, and for a period of time in the range of about 20 to about 120 minutes, and recovering an improved lubricating oil.

3. The process of manufacturing a lubricating oil of improved viscosity index, which comprises treating a lubricating oil with a reagent consisting of a mixture of substantially anhydrous hydrofluoric acid and iinely divided silver uoride in the presence of a low-boiling liquid hydrocarbon diluent, the volume ratio of oil to hydrofiuoric acid to light hydrocarbon being in the range of about 1:3:5 to about 5:3:1, the weight of silver fluoride to hydrofluoric acid being in the range of about 1 to about 10 weight per cent of the acid, said treatment of lubricating oil taking place at a temperature in the range of about 20 to about 300 C., at a moderate to high pressure, and for a period of time within the range of about 20 to about 120 minutes, and recovering an improved lubricating oil as a product of the process.

4. The process of manufacturing a lubricating oil of improved viscosity index, which comprises treating a lubricating oil with a reagent consisting of a mixture of substantially anhydrous hydrofluoric acid and solid iinely divided silver uoride in the presence of isopentane diluent, the ratio of oil to hydrofluoric acid to isopentane being in the range of about l:1:1, the weight of silver fiuoride to hydrouoric acid being in the range of about l to about 10 weight per cent of the acid, said treatment of lubricating oil taking place at a temperature in the range of about 20 to about 40 C., at about atmospheric pressure, and for a period of time within the range of about 20 to about 120 minutes, and recovering an oil of improved viscosity index as a product of the process.

5. A process according to claim 1 wherein a low-boiling hydrocarbon diluent is used in admixture with said oil and reagent.

PAUL H. CARNELL.

REFERENCES CITED rShe following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,366,743 Matuszak Jan. 9, 1945 2,375,675 Matuszak May 8, 1945 2,378,762 Frey June 19, 1945 FOREIGN PATENTS Number Country Date 292,932 Great Britain May 23, 1929 Certificate of Correction Patent No. 2,531,723 November 28, 1950 PAUL H. CARNELL It is hereby certied that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 4, lines 15 and 44, strike out the Word solid; line 26, same column, strike out nely divded;

and that the said Letters Patent should be read as corrected above, so that the :same Ina-y conform to the record of the case in the Patent Otce.

Signed and sealed this lst day of May, A. D. 1951.

[SEAL] THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

1. A PROCESS FOR IMPROVING THE VISCOSITY INDEX OF A LUBRICATING OIL WHICH COMPRISES TREATING A LUBRICATING OIL WITH A REAGENT CONSISTING OF A MIXTURE OF SUBSTANTIALLY ANHYDROUS HYDROFLUORIC ACID AND SILVER FLUORIDE. 